Sliders in DASD disk drives may be withdrawn from the magnetic disk surface prior to the shutdown of the disk drive in order to insure that the slider does not come into contact with the disk and also to prevent damage to the disk surface whenever the disk drive is repowered and the disks are again rotated. In larger disk drives, the space exists for a retraction and locking mechanism to hold the magnetic head and slider in a retracted position. As disk drives are reduced in size, space becomes a premium commodity and thus dictates that the withdrawal of the head from the surface of the disk be accomplished in a manner which consumes minimal space.
In more compact disk drives, sliders may be stored in a region of the disk surface which does not contain magnetic recording material or which would not contain any stored information that could be lost or damaged as a result of the contact of a magnetic head and slider with the surface of the disk. These areas are typically designated as landing zones. As the disk stops spinning, the air flow between the disk and the slider becomes depressurized and the slider, due to the preloading forces exerted thereon by the load beam, settles onto the surface of the disk.
In very small form factor DASD, the drive motors are not strong and do not provide large torques. Spin-up times may be significantly extended when sliders are in contact with the disks. In some cases the friction forces between the slider and the disk at the slider/disk interface are so large with regard to the torque of the drive motor that the motor will not start.
The lower velocity of the disk relative to the slider at the inner diameter of the disk results in less entrainment and fewer perturbations experienced by the slider, which leads to a lower likelihood of slider impact during the loading of the slider onto the disk.
Examples of landing zones on disk drive magnetic recording disks are disclosed in U.S. Pat. No. 4,139,874, issued to Shiraishi and U.S. Pat. No. 5,095,395, issued to Wakatsuki. Their landing zones do not remove the head from the surface of the disk or maintain it substantially spaced from the surface of the disk whenever the disk is in a non-powered condition.
Inner landing zones consume considerably less recordable area on the disk surface and, therefore, are preferred to landing zones disposed about the outer periphery of the disk.
Although landing zones do permit the landing of the slider in a region where no magnetic recording material and/or no recorded data exist, it is still preferable to remove the slider from the disk surface for storage in order that no damage can occur to the slider and magnetic head therein as well as to prevent damage to the recording magnetic disk surface upon restart. Removal of the slider also facilitates restart of the disk and disk run-up by minimizing start-up friction.
An example of an unloading device is disclosed in U.S. Pat. No. 4,752,848, issued to Garcia, et. al. The unloading device of Garcia, et. al., constitutes a high angle relatively steep ramp onto which the end of the load beam is engaged and forced onto in a direction substantially coaxial with the longitudinal axis of the load beam. The retention of the slider in a raised or removed position is dependent upon the continued force exerted on the load beam by an actuator mechanism. Without such actuator force, both the spring forces, known as preload exerted on the end of the load beam as well as the deflection forces stored in the load beam and actuator arm when forced toward the ramp, will cause the load beam to slide back down the inclined surface and will permit the magnetic head and slider to contact the surface of the magnetic recording disk. Garcia, et. al., requires some type of retention device to lock the actuator mechanism in the displaced position so that the sliders/magnetic heads are held withdrawn from the disk surface.